Former National Security Agency contractor Edward Snowden — a polarizing figure in the United States — has been avoiding extradition to the United States ever since he fled the country after being exposed as the source of high-profile leaks in 2013. Here’s a look back at how his case unfolded:

• June: Reports emerge showing the U.S. used a secret court order to force Verizon and other companies to hand over records from millions of Americans. Other stories, published in The Guardian and The Washington Post, detail the government’s PRISM program that lets the NSA take audio, photos, chats and documents from computers at Microsoft, Google, Apple and other companies.

• June 9: The Post and The Guardian identify Snowden as the source of the leaks. In a video interview, Snowden said the U.S. is crossing constitutional lines in its surveillance of citizens.

• June 14: Federal prosecutors in Virginia charge Snowden with espionage and theft of government property, as the U.S. seeks his extradition from Hong Kong.

• June 23: Snowden flies to Moscow, and his U.S. passport is revoked.

• Aug. 1: Snowden is granted temporary asylum in Russia, and spends the next year writing about the U.S. domestic surveillance system and sharing his experiences with conferences via video.

• 2014 — May 28: Snowden claims he was “trained as a spy in sort of the traditional sense of the word,” though government officials deny he ever was a U.S. spy.